Yes it does sound like your transmission is slipping. However the damage is probably already done. 75000 miles ago the hard shifting probablly lead to the slipping problem of today. A hard shifting is not always bad, sometimes the transmission is designed like this; however for an everyday driving tahoe, a hard shifting transmission is not desireable.
Hard shifting in your case is probably the result of the engine timing being a little bit off. It is impossible to check the timing on these engines with a timing light--you must use a scan tool that is capable of this proceedure. Unfortunatly, in most cases, this means a trip back to the dealer. In any case, if you have the timing checked, make sure you ask the mechanic before this proceedure is done, what the timing was when you brought it in and what it is now. The spec. On timing for these engines is + or - 2 degrees of top dead center.
Also unfortuanatly, it sounds like your transmission probably needs to be rebuilt or at least checked out by a reputable transmission shop. However you can try this, change the transmission fluid and filter. If you cannot do this yourself, tell the person who does this your transmission problem and ask them to look at the transmission fluid for any excessive clutch material or dirt in the fluid. Also ask them to look at the transmission filter screen for any excessive debris build-up. And ask them if the fluid smells and/or is burnt. This may help. Let me know how you make out.
Monday, December 31st, 2007 AT 11:46 AM